In the past three years, more than 3.4 million pounds of medication have been collected and incinerated, according to the DEA.

Hennepin County Sheriff Rich Stanek says unused drugs are often misused, and misuse often leads to abuse of illegal drugs, such as heroin.

"When people are doing open houses when they're selling their property people will use the bathrooms in those houses, sometimes even kids friends when they come over will go through the medicine cabinet," Stanek said. "You see stories all over this great state and across the country where these prescription drugs were diverted to something nefarious and that's where we run into problems."

He urges people to drop off prescriptions at designated law enforcement sites.

"It's much better than folks who would flush them down the toilet, put them out in the trash so they end up in the landfill," Stanek said. "What we want to do is dispose of these unwanted, unused, expired medications and the best way to do that is just turn them over to law enforcement. We don't ask any questions, we just want them removed."

Hennepin County collected nearly 10 tons of old medications last year.